Title: Attribute-based encryption without key cloning

Authors: M. Jason Hinek; Shaoquan Jiang; Reihaneh Safavi-Naini; Siamak F. Shahandashti

Addresses: Cheriton School of Computer Science, University of Waterloo, 200 University Ave West, Waterloo, Ontario, N2L 3G1, Canada. ' School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, China. ' Department of Computer Science, University of Calgary, 2500 University Drive, NW, Calgary, Alberta, T2N 1N4, Canada. ' Equipe Cryptographie, Département d'Informatique, École Normale Supérieure, 45 rue d'Ulm, 75230 Paris Cedex 05 – France

Abstract: In this work, we consider the problem of key cloning in attribute-based encryption schemes. We introduce a new type of attribute-based encryption scheme, called token-based attribute-based encryption (tk-ABE) that provides strong deterrence for key cloning, in the sense that delegation of keys reveals some personal information about the user. It also has the feature that a misbehaving user can be easily revoked. We formalise the security requirements for such a scheme in terms of indistinguishability of the ciphertexts and two new security requirements which we call uncloneability and privacy-preserving. We construct a privacy-preserving uncloneable token-based attribute-based encryption scheme based on Cheung and Newport's ciphertext-policy attribute-based encryption scheme and prove the scheme satisfies the above three security requirements. We also introduce the notion of non-interactive uncloneable attribute-based encryption in order to remove the online token server in the tk-ABE. We then construct such a new scheme with provable security. It should be pointed out that, although our non-interactive scheme is token-free, the scheme does not have the capability to easily revoke users from the scheme. Hence, both types of schemes have their own merits of existence.

Keywords: attribute-based encryption; ABE; access control; key delegation; user revocation; cryptography; key cloning; privacy preservation; security requirements.

DOI: 10.1504/IJACT.2012.045587

International Journal of Applied Cryptography, 2012 Vol.2 No.3, pp.250 - 270

Accepted: 12 Sep 2011
Published online: 26 Feb 2012 *

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